Editing Bohrium (section)

===Discovery===
Two groups claimed [[Timeline of chemical element discoveries|discovery of the element]]. Evidence of bohrium was first reported in 1976 by a Soviet research team led by [[Yuri Oganessian]], in which targets of [[bismuth-209]] and [[lead-208]] were bombarded with accelerated nuclei of [[chromium-54]] and [[manganese-55]], respectively.<ref>{{cite journal|doi=10.1016/0375-9474(76)90607-2|title= On spontaneous fission of neutron-deficient isotopes of elements | volume=273|year=1976|journal=Nuclear Physics A|pages=505–522  | last1 = Yu | last2 = Demin | first2 = A. G. | last3 = Danilov | first3 = N. A. | last4 = Flerov | first4 = G. N. | last5 = Ivanov | first5 = M. P. | last6 = Iljinov | first6 = A. S. | last7 = Kolesnikov | first7 = N. N. | last8 = Markov | first8 = B. N. | last9 = Plotko | first9 = V. M. | last10 = Tretyakova | first10 = S. P.}}</ref> Two activities, one with a half-life of one to two milliseconds, and the other with an approximately five-second half-life, were seen. Since the ratio of the intensities of these two activities was constant throughout the experiment, it was proposed that the first was from the isotope [[bohrium-261]] and that the second was from its daughter [[dubnium-257]]. Later, the dubnium isotope was corrected to [[dubnium-258]], which indeed has a five-second half-life (dubnium-257 has a one-second half-life); however, the half-life observed for its parent is much shorter than the half-lives later observed in the definitive discovery of bohrium at [[Darmstadt]] in 1981. The [[International Union of Pure and Applied Chemistry|IUPAC]]/IUPAP Transfermium Working Group (TWG) concluded that while [[dubnium-258]] was probably seen in this experiment, the evidence for the production of its parent [[bohrium-262]] was not convincing enough.<ref name="93TWG" />

In 1981, a German research team led by [[Peter Armbruster]] and [[Gottfried Münzenberg]] at the [[GSI Helmholtz Centre for Heavy Ion Research]] (GSI Helmholtzzentrum für Schwerionenforschung) in Darmstadt bombarded a target of bismuth-209 with accelerated nuclei of chromium-54 to produce 5 atoms of the isotope bohrium-262:<ref name="262Bh">{{cite journal
|last1=Münzenberg
|first1=G.
|last2=Hofmann
|first2=S.
|last3=Heßberger
|first3=F. P.
|last4=Reisdorf
|first4=W.
|last5=Schmidt
|first5=K. H.
|last6=Schneider
|first6=J. H. R.
|last7=Armbruster
|first7=P.
|last8=Sahm
|first8=C. C.
|last9=Thuma
|first9=B.
|year=1981
|title=Identification of element 107 by α correlation chains
|journal=Zeitschrift für Physik A
|volume=300
|issue=1
|pages=107–8
|doi=10.1007/BF01412623
|bibcode = 1981ZPhyA.300..107M
|s2cid=118312056
|url=https://www.researchgate.net/publication/238901044
|access-date=24 December 2016
}}</ref>

:{{nuclide|link=yes|bismuth|209}} + {{nuclide|link=yes|chromium|54}} → {{nuclide|link=yes|bohrium|262}} + {{SubatomicParticle|link=yes|neutron}}

This discovery was further substantiated by their detailed measurements of the alpha decay chain of the produced bohrium atoms to previously known isotopes of [[fermium]] and [[californium]]. The [[International Union of Pure and Applied Chemistry|IUPAC]]/IUPAP Transfermium Working Group (TWG) recognised the GSI collaboration as official discoverers in their 1992 report.<ref name="93TWG">{{Cite journal
|doi=10.1351/pac199365081757
|title=Discovery of the transfermium elements. Part II: Introduction to discovery profiles. Part III: Discovery profiles of the transfermium elements
|year=1993
|author=Barber, R. C.
|journal=Pure and Applied Chemistry
|volume=65
|pages=1757
|last2=Greenwood
|first2=N. N.
|last3=Hrynkiewicz
|first3=A. Z.
|last4=Jeannin
|first4=Y. P.
|last5=Lefort
|first5=M.
|last6=Sakai
|first6=M.
|last7=Ulehla
|first7=I.
|last8=Wapstra
|first8=A. P.
|last9=Wilkinson
|first9=D. H.
|issue=8|s2cid=195819585
|doi-access=free
}}</ref>